Battery Issues

When I heard the iPhone 4 battery would have 40% more capacity I was jazzed. Knowing the kind of life I get from the iPad I had faith it would be true. Fact is, I'm getting worse battery life than I got with a two year old 3G.
When I got the 4 at the AT&T store on the 29th it took the rep ten minutes to get the phone to begin accepting a charge just to do the activation. I thought that was odd. Every other iPhone I've bought had some juice in it out of the box.
Last night I charged the phone and turned it off before bed. When I got up ( eight hours later) and turned it on the battery meter read half charged!!! I now believe the battery is defective. Anyone else have similar issues?
TIA,
Carl

I agree on the battery life. Mine is far shorter than my previous 2g, or 3G. Different than what you mention however, my charges pretty fast. I am having to charge mid-day from the start of the morning. Puzzling...

I called Apple and they set me up for a replacement appointment. When I arrived the rep asked that he run a diagnostics on the battery. He said it checked out fine but I had EVERY APP IN THE PHONE RUNNING! I wasn't well versed on "multitasking" and was not aware that when you launch an app it stays running in the background until you remove it from the multitasking bar. He asked that I try the phone again for a few days and that if I wasn't happy still they would replace the phone.
Well battery life has dramatically improved so user error appears the be the problem.
I might add that Apples pseudo "multitasking" function is cumbersome at best, adding multiple keystrokes, and I personally would like to be able to turn it off.
The fact that I lost significant battery power with the phone OFF is still a mystery however.

I called Apple and they set me up for a replacement appointment. When I arrived the rep asked that he run a diagnostics on the battery. He said it checked out fine but I had EVERY APP IN THE PHONE RUNNING! I wasn't well versed on "multitasking" and was not aware that when you launch an app it stays running in the background until you remove it from the multitasking bar. He asked that I try the phone again for a few days and that if I wasn't happy still they would replace the phone.
Well battery life has dramatically improved so user error appears the be the problem.
I might add that Apples pseudo "multitasking" function is cumbersome at best, adding multiple keystrokes, and I personally would like to be able to turn it off.
The fact that I lost significant battery power with the phone OFF is still a mystery however.

You are right about the mystery. The explanation makes no sense at all. If your phone is fully turned off (and not just asleep) then you have no apps running. And when you phone is on, all the apps 'running' in the background are not really running. They are termination but their state is held in memory. This should have negligible to no impact on battery. This is specifically why Apple implemented their form of multitasking-resource (specifically battery and CPU) conservation. Some of the multitasking APIs, like background music, location services and maybe VOIP would utilize CPU when running in the background, but should really be only 3 processes, regardless of the number of apps you actually have 'running' in the background.

I would have guessed a bad battery or bad battery metering.

"My 8th grade math teacher once said: "You can't help it if you're dumb, you are born that way. But stupid is self inflicted."" -Hiro.